There are more 4s and 5s than 1s and 2s, so the mean of the unknown players is probably somewhere between 3 and 4.
On the other hahd, if you have a lot of very active and competitive teams in your league, any 4's they know about, but who are unknowns to you, will be up towards the top of their lists, and won't be left for you to pull at random. And any 1's will be at the bottoms of your list. So while the unknowns for you should have the same distribution, the ones available to you in the draft will tend to be lower.
These players will probably be your #3 pick. Now that we have a lot of established teams, we may be at the stage where we can only absorb 1 or 2 draftee per team, replacing an older player or someone past prime training. A 3 might not be good enough to cut it. So you still might be better off going totally blind and getting a 4 for your 3rd pick.